250 integral head - replace exhaust manifold?

[stomper]

Anybody ever replaced an exhaust manifold on an integral head straight 6? I haven't looked it over close yet but is this even possible? I understand the intake is cast in the head but the exhaust manifold is separate? Just want to eliminate the sound from the large hole until I get around to a V8 swap.

[stomper]

I think I figured it out from this thread:

http://67-72chevytrucks.com/vboard/s...d.php?t=563859

Yes. Anyone have horror stories tho?

[Palf70Step]

When I disassembled mine for a rebuild, many (most) of the bolts that held the exhaust manifold in place snapped off. Since I was going to old style (non-integrated head) it didn't bother me as much. Not sure how you could pre lube/penetrating oil on them to lessen that chance. The last time I did one was 30 years ago and I remember the bolts breaking off that one also. That is the only issues I have seen with the exhaust manifold.

[cadillac_al]

If you have room for an impact wrench in there that may help with the broken bolt threat.

[ElGracho]

Originally Posted by Palf70Step

When I disassembled mine for a rebuild, many (most) of the bolts that held the exhaust manifold in place snapped off. ...

This.

My engine is getting changed because of this. The bolt fragments are hard as rock from the heat cycling. I tried all the tricks to get them out. Considered changing the head to an old style, but 5.3 LS motor got chosen instead...

[stomper]

It appears the bolts are all threaded into the exhaust manifold which is junk anyway. If I break them all off I'm still okay as long as I can find a good exhaust manifold. No luck online yet. Otherwise yeah I guess it's LS swap.

[VWNate1]

There are new ones out there, I think Summit Racing sells them, I searched and found them in Florida for $150 brandy new .

Cast iron, Chinese made I'm pretty sure .

Used ones are out there, I have a few originals somewhere .

[stomper]

Originally Posted by VWNate1

There are new ones out there, I think Summit Racing sells them, I searched and found them in Florida for $150 brandy new .

Cast iron, Chinese made I'm pretty sure .

Used ones are out there, I have a few originals somewhere .

Got a link!!???

[stomper]

Boy did I get lucky! Found this truck in my local yard. Manifold looks good. Even has PS and PB. Wish me luck on the bolts.

[VWNate1]

Sonofagun ~ you found it ! .

I hope you'll be able to disable the E.G.R. valve.....

In case that one snaps too many studs / bolts, here's the link to new ones, I have NO REGRETS :

https://www.google.com/search?client...haust+manifold

[stomper]

Originally Posted by VWNate1

Sonofagun ~ you found it ! .

I hope you'll be able to disable the E.G.R. valve.....

In case that one snaps too many studs / bolts, here's the link to new ones, I have NO REGRETS :

https://www.google.com/search?client...haust+manifold

Hey Nate that's just a Google search for a 6 cyl exhaust manifold. Of course I can do that. This is an INTEGRAL HEAD motor. Not the same.

[VWNate1]

Damn, sorry .

? Do you have the casting # off the old exhaust manifold ? .

[stomper]

Originally Posted by VWNate1

Damn, sorry .

? Do you have the casting # off the old exhaust manifold ? .

473369. Note the crack and PO's repair. Here's what it's in. I see one on ebay. The studs are bent and at least 4 bolts are broken off. With shipping its $200.

https://rover.ebay.com/rover/0/0/0?m...2F254193068579

[VWNate1]

? That's your truck ? .

I like it ~ just what a light truck is supposed to be : simple and direct, ready for work .

That used one will be a challenge to fix, getting the broken studs out is tricky for me .

? What happened to the one you showed in a junkyard ? .

[VWNate1]

It's been a while since I worked at a GM Dealer but they used to be able to do a nationwide computer parts search, now that you have the #, maybe go to your local GM (any GM Dealer can run GM part #'s regardless of brand) and find one languishing some where.....

I found more than a few parts fpr my old 1949 Chevy 3100this way .

I'm searching but wow, this is a hard to find part .

[stomper]

Yes that's my truck. Yes the manifold is hard to find. That junkyard manifold is removed and at a local cast iron weld shop. It's all he does and he has white hair. It's not cracked, it is nice but he's removing 4 broken bolts. Didn't trust myself with it. See how lucky I was?

[VWNate1]

Oh yes ! I know exactly how lucky you are I've been running InLine 6 bangers since the 1960's and love them and know the difficulties .

When your truck was new I did parts support for them in a Municipal fleet, they were fantastic rigs *but* had serious casting flaws in the cylinder heads and few made it past 20,000 miles before cracking irreparably, at one point I had about 30 of them lined up waiting for GM to release the new, revised and crack resistant cylinder head, over 12 months waiting, at that time you could by a two year old 1/2 ton pickup for maybe $1,200 with a bad head and no replacement in sight .

We held on to ours and repaired everyone, they were all still running like new (with revised cylinder heads) when we salvaged them years later .

Once you get this sorted out you're going to love this truck .

[stomper]

That's quite a story VW. Thanks for sharing that with us. Hopefully my motor has one of the new and improved heads and I'm not wasting my time with this exhaust manifold.

[VWNate1]

Any older Journeyman Mechanic has more stories than they can remember .

I'm luckier than you as I grew up working with and on, pre WWII ~ early 1960's vehicles and as farm vehicles most were i6 powered .

I could care less about spinning the tires, I drive my jalopies 800 + miles every seven days and all are 'junk' .

GM knew _exactly_ what they were doing when they designed and released the '73 ~ '87 'Square Bodied' trucks ~ the bodies were cheap tin foil but the rest of the rigs were still packed with good engineering , cheap to purchase and operate,cheaper yet to repair .

[stomper]

I was successful! Manifold is in and it purrs like a kitten. Old one was broken completely in half.

[Palf70Step]

Good to hear!

[VWNate1]

Whew, that old one looks bad .

Question ? .

Do the outer ends of the exhaust manifold have pins, studs and nuts or bolts ? .

I ask because on the previous engines many replace the outer pins with bolts or studs & nuts and so force the manifolds to crack .

[stomper]

Originally Posted by VWNate1

Whew, that old one looks bad .

Question ? .

Do the outer ends of the exhaust manifold have pins, studs and nuts or bolts ? .

I ask because on the previous engines many replace the outer pins with bolts or studs & nuts and so force the manifolds to crack .

Those two bigger holes are just thru holes. I don't think there was any feature in the head there but maybe was a pin. Definitely no fastener.